1 Field of the Invention
The present invention relates to a holder for an abrasive disc and specifically a holder for a relatively large size abrasive discs.
2 Description of the Prior Art
Prior art abrasive disc holders have included a center portion having an attachment means that interlocks with a complementary attachment means on the abrasive disc. A rubber backing member generally extends outward from a center portion to provide for a flexible support of the abrasive disc during operation. One type of prior art holder for an abrasive disc included a metallic center portion and with a stud member projecting through the metallic portion and with the stud member including a threaded end. The large size disc includes an attached nut member such as a sheet metal nut member having a flange on the abrasive surface of the disc and with the nut projecting backward through a hole in the disc. The nut member may be attached by fingers which extend backward through the disc and bent over. The nut member cooperates with the threaded end of the stud so that the disc may be locked onto the holder by threading the nut member on to the end of the stud and with the disc compressed between the flange portion of the nut member and the metallic portion of the holder as the disc is tightened on the holder.
In prior art, the metallic center support portion and stud are fixed in position and during use of the abrasive disc, the torque causes the nut member to lock onto the stud with greater and greater holding force. Therefore, with the prior art devices the abrasive disc member can become locked very tightly onto the holder so that it becomes difficult to remove the abrasive disc when it is necessary to change the abrasive disc. In addition, since abrasive discs have a certain compressability, the region around the center hole of the disc that lies between the flange of the nut and the metal center of the holder is highly compressed as the nut is tightened by operating torque and acts in the manner of a spring-type lock washer to further lock the nut on the stud.